Electrical and optical properties of erbium-related centers in 6H silicon carbide

Abstract

Implants of Er, Al and N with energies ranging from 120 keV to 2 MeV were carried out in n- and p-type 6H-SiC. The aim is to identify electrically active defects in the bandgap which can be associated with the 1.54 μm Er 3+ luminescence in 6H-SiC. Measurements are conducted by means of deep level transient spectroscopy (DLTS) as well as low temperature photoluminescence (LTPL). In n-type 6H-SiC implanted with Er, we find well known DLTS damage levels whereas strong characteristic lines of Er 3+, near 1.54 μm, are seen in the photoluminescence. In p-type 6H-SiC implanted with Er two DLTS peaks can be uniquely associated with the Er 3+, on the other hand, no luminescence is observed. Conversion of such p-type 6H-SiC into n-type, by nitrogen implantation, recovers the photoluminescence. We conclude that the Er-associated defect levels in the lower half of the gap are likely not involved in the energy transfer mechanism which is responsible for the 1.54 μm luminescence.